To study the signal of gene flow between West and East Eurasian populations (European and Asian populations in Table 1), firstly we performed Principal Component Analysis (PCA) both with and without respectively African populations based on 96,538 random SNPs avoiding high linkage disequilibrium.We observed that some clusters of West and East Eurasians are slightly shifted towards each other, indicating potential admixture between them (Fig. There is a clear ‘cline’ between West and East clusters.
In the current study, our samples did not cover all European regions.
For example, Southern European populations were not included in the analysis because they may have been affected by a recent genetic contribution from populations with African ancestry.
(b) Fine resolution of the PC plot after removing YRI.
Both plots were based on 96,538 pruned SNPs to reduce linkage disequilibrium relationships..
One Oceania population Papuan, which were not considered experiencing any recent admixture with EUR or EAS, was added into our model as an out-group), and each group should fall along a line with a negative slope (equation (3)) if most groups shared same degree of drift T and W.
By carrying out the least-squares that best fit all EAS data, we could estimate the parameters of the linear model, allowing us to calculate the admixture proportion for each group.As a result, based on phylogeny as Supplementary Fig.S1, Dai from southern China could be considered to be a surrogate of ancestral EAS (Fig. Similarly, we applied our approach for each pair of EUR and found French holds the less genetic contribution from EAS than other EUR, and therefore can be considered as a surrogate of ancestral EUR (Fig. We assumed a Hybrid Isolation (HI) model for admixed Eurasian populations with ancestries from both EUR and EAS, as shown in Supplementary Fig. For each group of EAS, we assessed whether the statistic f), significantly deviates from zero (see Methods). Otherwise, the population should have entire EAS ancestry.Here we present what is, to the best of our knowledge, a systematic investigation of genetic admixture between different European and Asian populations using genome-wide single nucleotide polymorphism (SNP) data from 34 populations, including seven European groups (EUR), 9 Central or South Asian groups (CSA), and 17 East Asian groups (EAS) and one Tibetan group from Tibet Plateau.Based on statistical analysis using 4 Population Test (f, we detected gene flow between Europeans and Asians were prevalent for most populations including even those from west-northern Europe and East Asia which have been generally regarded as less admixed.Several studies have revealed evidence of sub-Saharan African admixture among southern European populations but only rarely among northern European populations.